Space Charged Limited Currents in Liquid Dielectrics

Abstract

The majority of conduction experiments in liquid dielectrics are based on the use of metal electrodes, but the metal-to-dielectric interface acts as a blocking contact, or at best a poor injector. Charge injection from metal electrodes does set in at high fields, but it occurs from microscopic asperities on the electrodes, so the emission is nonuniform. For the purpose of studying charge transport phenomena, therefore, experimental techniques are required that provide a uniform, copious source of charge carriers, and several approaches to this have been proposed: for example, Adamczewski [1], Freeman [2], Schmidt [3] Hummel and Allen and others have used x-rays to introduce excess carriers into dielectric liquids; Silver et al. [4] have shown that the tunnel junction can be used as an injecting electrode; members of the CNRS group have exploited the ion-exchange membrane as an injecting contact [5]. LeBlanc [6] used a photocathode to inject electrons into hydrocarbon liquids; Hartmann and Schmidlin [7] used a photoconductive layer as an injecting contact, and Watson, Schneider, and Till [8] have used an electron beam as an ohmic contact.